Thassa, Deadly Fugitive

Deathtouch.

Whenever you cast an instant or sorcery spell you
may pay {2}, if you do so, exile it under Thassa.
{b},{t} Copy and play a card with converted mana cost of 3 or less from exile.
{4}{b}{b} Deal {x} damage divided however you want between any target, where {x} is the total mana cost
of the cards exiled under Thassa, then put those cards in your graveyard.